That was tons of fun. The performances were all around great, the amount of gore was just right, the action scenes actually had some intensity and originality. David Tennant stole the show, completely. I really do kinda miss him as the Doctor (not that I dislike Matt Smith.)
I'm also glad they didn't go for a cheap "shock ending." Let's just let the hero enjoy that which he has earned through his (literal) trial by fire.
So yeah, I enjoyed the crap out of it. There really doesn't seem to be any major thing I can nitpick. Is it sad that in this day and age it's refreshing to see a movie about vampires that are actually evil